Greenland Glacier Change Index

On April 2, 2015May 3, 2024 By mspeltoIn glacier climate change, Glacier Observations, Greenland glacier retreat

This is an index of posts on the response of specific Greenland glaciers to climate change. In the 1980’s when I first worked on Jakobshavn Isbrae, Greenland there was not much research occurring on the glaciers. Today in response to the dynamic changes discussed below and glacier by glacier in the index links, Greenland is the focus of numerous extensive, ongoing and important research projects. In 2015 scientists are gearing up for the main field season to better identify and understand the current and future response of this critical ice sheet. At the time of each post I reference the specific research relevant, the posts are from 2009-2014. In the intervening period new research has made some further advances, and I will endeavor to update each post to reflect this. The posts illustrate the significant response of Greenland Glaciers to climate change regardless of what type of glacier they are. The Polar Portal has developed an online viewer of change on selected glaciers. Each year the Arctic Report Card updates annual observations of Greenland Ice Sheet Change. The posts have benefitted from the insights and observations of Espen Olsen. Any questions about a glacier or suggestions on a glacier to look at let me know.

Greenland

Humboldt Glacier
Petermann Glacier
Kuussuup Sermia
Thrym Glacier Retreat
Tiningnilik Glacier Lake
Jakobshavn Isbrae
Zachariae Isstrom
Umiamako Glacier
Alison Gletscher
Dodge and Storm Glacier
Kong Oscar Glacier
De Reste Bugt
Qaleraliq Glacier
Upernavik Glacier
Apuserajik Glacier
Epiq Sermia
Sarqardliup Seremia
Narssap Sermia
Steensby Glacier
Sortebrae Glacier, Greenland
Tracey Gletscher
Nioghalvfjerdsbrae-79 Glacier
Steenstrup Glacier
Rinks Gletscher
Puisortoq
Mittivakkat Glacier
Ryder Glacier
Kangiata Sermia
Koge Bugt

Base Map above right indicates the glacier types 1-4 distribution and key glacier locations with specific posts below. P=Petermann, R=Ryder, S=Steensby, H=Humboldt, Z=Zacharaiae, D=De Reste Bugt, T=Thyrm, N=Narssap Sermia, J=Jakobsan, E=Epiq Sermia, U=Umiamako, K=Kong Oscar.

Variations in Greenland Ice Sheet outlet glacier behavior

The Greenland Ice Sheet has an area of 2.17 million square kilometers (1.28 million square miles) and spans 18 degrees of latitude from north to south. It is not surprising that over this vast area that the geology and climate vary substantially and that this leads to variations in behavior of Greenland glaciers. Our tendency is to lump the Greenland Ice Sheet into one category impacted similarly by each of the dynamic forces that impact flow. This is akin to saying banks, credit unions and savings and loan institutions are impacted similarly by all the economic forces. In the case of a recession there is a shared signal, just as with global warming there is a shared signal among Greenland glaciers. This is a simplification that does not work. In this article we divide the glaciers into four main categories to illustrate the different properties and sensitiveness of each. This is an updated version of an article Dan Bailey and I wrote first for Skeptical Science, updated here with links above to the individual glaciers that emphasize the specific changes and with new references. In recent years the most striking aspect of Greenland Glaciers is that the signal of change is so strong and on so many of the different glaciers. The specific response is different, which if we try to lump the glaciers into one category, makes the data look noisy. Instead if we look at the response of glaciers with similar dynamics than the signal of response is strong indeed. Csatho et al (2014) note the variation in ice thickness across the ice sheet for the 1993-2012 period and that 48% of the thinning is driven by ice dynamics. The net loss is an equivalent contribution of 0.67 mm/year to sea level rise.

Greenland glaciers fall into at least 4 common types, each with its own unique sensitivity to sea surface temperature, surface melting, meltwater lubrication, calving changes, etc.

Type 1: Northern, with Large Floating Termini
Northern glaciers with large floating termini (Petermann, Ryder, Steensby, Zachariae, Academy, etc). Each of these is a marine terminating outlet glacier that has an extensive floating ice shelf. The large ice shelves can exist in part due to the lower surface melt rates and the lower flow rates of the glacier. Petermann Glacier is the fastest with a flow speed of 1000 m/year at the grounding line. This is much less than the average outlet glacier speed along the west coast. The large floating ice shelves are susceptible to bottom melting but, except for Petermann Glacier, we have no observations of the process or that more warm water is penetrating under these ice shelves. Rignot and Steffen (2008) found that at Petermann Glacier 80% of the ice loss into the ocean was from basal melting of the floating tongue. If the ice shelves are removed, the feeding glacier is less buttressed and will accelerate for a period and draw down its surface profile. The recent ice area lost by Petermann, Steensby, Academy and Zachariae Ice Stream indicate these glaciers are being impacted by the increased melting at the surface and likely the base of the ice shelf for Petermann Glacier at least.

Examination of how far the high velocities extend inland in Figure 2 and 3 indicates that it is only Zachariae and Petermann that tap far into the ice sheet. This northern area has low accumulation rates, and a shorter less intense melt season. The early onset of melting and lack of accumulation in 2010 led to an early exposure of the ablation zone on these glaciers. This is their sensitivity Achilles Heel: relatively little increases in melt can expand the ablation zone appreciably given the low surface slopes and low accumulation rates. Based on the velocity map, it is the Zachariae that is likely the only of this group that would be comparable to a bank that is too big to fail as its increased velocity band extends well into the ice sheet (Joughin et al, 2010).

Figure 1. Velocity of Petermann and Humboldt Glacier, the latter does not have a deep bedrock trough extending to the heart of the GIS.

Fig 2. Ice flow speed for Zachariae Glacier (Joughin et al, 2010)

Type 2: Inland-terminating
Glaciers with inland termini lacking any calving (Sukkertoppen, Frederickshaab, Russell, etc). Between the fast flowing marine terminating outlet glaciers, the ice sheet particularly in the southwest quadrant has numerous glaciers that terminate on land or in small lakes. The velocity of these glaciers reaches a maximum of 1-2 meters/day. Each terminates on land because total ablation over the glacier equals total accumulation at the terminus. These glaciers are more like a typical alpine glacier and are susceptible to the forces that tend to cause alpine glaciers to experience peak flow during spring and early summer. Those forces are the delivery of meltwater to the base of the glacier, when a basal conduit system is poorly developed. This leads to high basal water pressure, which enhances sliding. As the conduit system develops the basal water pressure declines as does sliding, even with more water. In the long run it is not clear that more melt will lead to sustained higher velocities as a more efficient drainage system leads to lower basal water pressures. Sundal et al, (2011), best illustrated this.

Fig 3. An example of a two-dimensional ice-velocity map of the study area in southwest Greenland Inland terminating glaciers velocities (Sundal et al, 2011).

This is what has been recently reported to be the case by Sundal et al (2011). The meltwater lubrication mechanism is real, but as observed is limited both in time and area impacted. It is likely that, as on alpine glaciers, the seasonal speedup is offset by a greater slowdown late in the melt season. Most observed acceleration due to high meltwater input has been on the order of several weeks, leading to a 10-20% flow increase for that period. The role of supraglacial lakes in this has been a point of emphasis; Luthje et al, (2006) noted that the area covered by supraglacial lakes was independent of the summer melt rate, but controlled by topography. This led Luthje et al (2006) to conclude that the area covered by supraglacial lakes will remain constant even in a warmer climate. This suggests that the enhancement of flow by the drainage of such lakes would be limited.

The land terminating glaciers such as Sukkertoppen, Russell and Mittivakkat are retreating significantly in response to global warming. This is an indication of negative mass balance. The latter glacier in southeast Greenland has retreated 1200 meters since 1931 (Mernild et al, 2011). The Mernild study identified this slow rate compared to the outlet glaciers and, based on mass balance observations, that the current surface mass balance can only support a glacier at most one-third its current size. This indicates the slow but inexorable sensitivity of the non-calving glacier to surface mass balance change. Moon and Joughin (2008) observed that the retreat of the land terminating glaciers was relatively minor from 1992-2007, averaging 5 m/year or less. These glaciers are the equivalent in our banking system to the local banks: there are many and they are sensitive, but the changes in a single one is not important.

Type 3: Marine-terminating
Fast flowing marine terminating outlet glaciers of western and southeast Greenland (Rinks, Umiamako, Helheim, Jakobshavn, Epiq Sermia, etc). These are the glaciers that drain the greatest area of the ice sheet and deliver the greatest volume to the oceans via calving. The flux from many of the larger glaciers is over 10 km3/year (DMI). Each of these glaciers is fast-flowing at the terminus; the fast flow section extends inland into the ice sheet up a sub-glacial trough. The outlet glaciers act like a drain capturing ice from a larger area of the ice sheet than their narrow terminus would suggest.

Figure 4. Umiamako Glacier is typical with the highest velocity near the calving front and the high velocity ice stream extending back into the ice sheet.

Figure 5. Jakobshavn Glacier terminus retreat, the recent retreat has been associated with thinning and faster flow.

Pelto et al (1989), a paper on the equilibrium state of the Jakobshavn Glacier, showed that the terminus had not changed significantly in 30 years; its velocity had also been consistent. Furthermore, it was observed that the velocity was consistent throughout the seasons. This indicated that the glacier velocity was not being impacted by the meltwater pulse each summer.

Bob Thomas (NASA, 2004) and Terry Hughes (University of Maine, 1986) developed the basic mechanism of flow for the glacier that has proven to be true. The outlet glaciers have a balance of forces at the calving front. The fjord walls, the fjord base and the water column impede flow. The slope of the glacier, its upglacier velocity and the height of the calving face strive to increase flow. If the glacier thins than there is less friction at the calving front from the fjord walls and the fjord base, leading to greater flow. The enhanced flow leads to retreat and further thinning, resulting in the thinning and the acceleration spreading inland. In 1990 it was not envisioned that acceleration would occur as soon as it has, yet that was the motivation for the research.

Fig 6. Jakobshavn profile (Thomas et al, 2009)

In 2001 acceleration of Helheim, Jakobshavn and Kangerdlussaq Glacier caught the attention of the world. By 2007, acceleration had been noted at all 34 marine terminating outlet glaciers observed.

The acceleration was not significantly seasonal; Howat et al (2010) noted a 15% seasonal component to the acceleration, it had spread inland and had led to retreat and thinning. This demonstrated that the marine terminating glaciers were largely responding to a change in the balance of forces at the glacier front.

Fig 7. Ice flow velocity as color over SAR amplitude imagery of Jakobshavn Isbræ in a) February 1992 b) October 2000. In addition to color, speed is contoured with thin black lines at 1000 m/yr intervals and with thin white lines at 200, 400, 600, and 800 m/yr. Note how the ice front has calved back several kilometers from 1992 to 2000. Further retreat in subsequent years caused the glaciers speed to increase to 12,600 m/yr near the front. (Ian Joughlin, Big Ice)

The recent increases in outlet glacier discharge have always been coincident with partially floating ice tongue losses. This causes reduced back pressure at the glacier front, letting up on the brakes; the resulting glacier thinning leads to less basal friction and further acceleration. If the glacier front retreats into deeper water the process will continue and increase. This is why understanding the basal slope changes inland of the calving fronts is crucial. Moon and Joughin (2008) observed the terminus change of 203 glaciers from 1992-2007 and noted a synchronous ice sheet wide retreat of tidewater outlet glaciers. The thinning could be due to increased surface melt, basal melt or most likely a combination of the two. Certainly the supraglacial lake drainages are not the key as the widespread acceleration in the southeast and southwest Greenland, yet the southeast has less than 10% of the lakes of the southwest , as documented by Selmes et al (2013) in a paper submitted to the Cryosphere.

Moon and Joughin (2008) reported for the 2000-2006 period:In the southeast quadrant 35 glaciers retreated an average of 174 m/year. In the eastern quadrant 21 glacier retreated an average of 106 m/year. In the northwest 64 glaciers retreated an average of 118 m/year. Each quadrant’s retreat increased markedly after 2000. In east central Greenland Walsh et al (2012) noted the retreat of all 37 outlet glaciers examined. Bjork et al (2012) note the terminus change in 134 east Greenland glaciers, idenitifying the last decade as the most rapid for marine terminating glaciers but not land terminating glaciers. The largest of this group are comparable to the banks that are too big for our banking system to allow them to fail: they drain a substantial portion of the entire ice sheet and reach so far into the ice sheet that their behavior can impact that of other adjacent glaciers.

Type 4: Marine-terminating in Shallow Water
Marine terminating glaciers outlet glaciers in shallower water (Humboldt, Cornell, Steenstrup etc). These glaciers do have calving termini, but lack the large fast flowing feeder tongues extending into the glacier. This is because there is not a topographic low under the ice sheet that funnels the flow. Humboldt Glacier is the widest front of any Greenland Glacier, wider even than Petermann Glacier. However, the velocity on average is low at 100 m/year and the base of the glacier is quite high. This makes it difficult for a large calving retreat of the glacier to occur and extend inland. Humboldt Glacier is retreating but as the velocity profile indicates the glacier, despite its size, does not tap dynamically into the center of the ice sheet. These glaciers are substantial, but their failure (though significant for sea level) would not destabilize the ice sheet as a whole. Naarsap Sermia would be another example in southwest Greenland. Dodge and Storm Glacier an example in northwest Greenland.

Fig 8. Humboldt profile (Thomas et al, 2009)

The amazing aspect of Greenland glaciers is that (despite the specific variation in type, location specific fjord configuration, etc) their response has been as uniform and synchronous to global warming as has been observed. If this warming of the world persists long enough, the ice “banks” of Greenland will begin to fail. Those with the greatest reserves on their asset sheets and the fastest turnover, and thus having the greatest potential contributions to sea level rise over time, are: In the north, Zachariae (and to a lesser extent, Petermann). The fast flowing marine terminating outlet glaciers of western and southeast Greenland (Rinks, Umiamako, Helheim, Jakobshavn, Epiq Sermia and Kangerdlussaq).

The surface mass balance of the glacier is the difference of accumulating snow on the ice sheet (its income) and snow and ice losses from melting and calving (its expenditures). The volume of the ice sheet is its asset. On an ice sheet, the main factor driving flow is simply the mass balance input in the accumulation zone. The higher the accumulation rate the faster the movement; the accumulated snow is inexorably moved downslope towards the ocean and the margin of the ice sheet. Observation of a precipitation map (focused not on the outer margin, but on the accumulation zone of the ice sheet) indicates that highest accumulation rates, over 40 cm per year, extend along the western side of the ice sheet to the southeast quadrant of the ice sheet. The southeast quadrant also has many fewer surface lakes than the southwest quadrant.

Figure 9. Mass balance in Greenland from Van Den Broecke et al, (2009)D denotes change in ice discharge while SMB denotes the net surface mass balance (accumulation minus ablation).)

Fig 10. Distribution of precipitation in Greenland (in grams per square centimeter per year). Contours dashed where inferred. Ice-free areas are shown in dark gray. (USGS, Satellite Image Atlas of Greenland)

The overall topography of the ice sheet is controlled both by the basal and peripheral geology and the mass balance distribution of the ice sheet. The higher rates of mass accumulation inland and the greater melting nearer the margin yield a steeper profile for the ice sheet.

Figure 11 shows that the contours have the closest spacing along the west margin and in the southeast, just as the high accumulation rates in those areas would suggest. Thus the combination of the surface slope and the accumulation rate drive faster flow in these regions.

Climate change has led to an observed increase in surface melting, surface accumulation, increased discharge and overall mass balance losses. The very mechanism that establishes the basics of behavior of the GIS mass balance are changing (Zwally et al, 2011). This is leading to most Greenland glaciers retreating, most outlet glaciers accelerating, an increase in the number and elevation of Greenland lake, expanding melt extent on the ice sheet. The 2012 seasons extraordinary ice melt extent is illustrated by the video below of Marco Tedesco’s melt extent data set. .

Leroux Bay Glacier Retreat-Island Formation, Antarctic Peninsula

On March 30, 2015May 3, 2024 By mspeltoIn Antarctic Glacier retreat, glacier climate change, Glacier Observations1 Comment

Leroux Bay is on the west coast of the Antarctic Peninsula in Graham Land. Numerous glacier drain from the Antarctic Peninsula into the ocean along this coast, and as they retreat the coastline is changing. Air temperatures rose by 2.5°C in the northern Antarctic Peninsula from 1950 to 2000, which has led to recession of 87% glaciers and ice shelves on the Peninsula in the last two decades (Davies et al.,2012). Most spectacularly has been the collapse of Jones, Larsen A, Larsen B, Prince Gustav and Wordie Ice Shelves since 1995 (Cook and Vaughan, 2010). This has opened up our ability to examine sediments that had accumulated beneath the floating ice shelves. The LARISSSA Project has been pursuing this option and utilized the Korean icebreaker ARAON to explore and map the bathymetry of Leroux Bay. Last week Antarctica recorded its highest temperature at the Argentine Base Esperanza on March 24th, 2015 located near the northern tip of the Antarctic Peninsula reported a temperature of 17.5°C (63.5°F). Here we examine the changes from 1990 to 2015 of glacier on the north side of Leroux Bay.

Location of Glacier examined from USGS Map.

Google Earth image indicating glacier flow directions, blue arrows, island yellow arrow and glacier terminus red arrow.

In 1990 and 1991 the Leroux Bay Glacier extended to the yellow arrow, which is an island connected by the glacier to the mainland and acts as a stabilizing point for the glacier. The ice front is marked with yellow dots in both cases. The terminus region of the glacier is floating, making this a small ice shelf, fed by three tributaries, one from the north, one from the east and one from the northeast. By 2001 the glacier front has retreated to the red arrow, losing most of the floating area, and the northern tributary now has an independent calving front. The red arrow also points to the tip of a peninsula, another stabilizing point, the ice front is marked by the red dots for 2001 and 2015. The yellow arrow indicates the new island that is detached from the mainland. The two images from January 2015 and Late February 2015 indicate limited retreat an the north and south sides of the terminus, but retreat in the glacier center has led to a concave shaped calving front. Retreat from 1990 to 2015 averages 2.1 kilometers. The USGS map (Blue Line) indicates the terminus in the 1960’s was 3 km beyond the 1990 terminus location. The calving front remains active with extensive crevassing. It is not clear simply from Landsat imagery if any of the glacier is afloat, if so it would likely be the southern half of the eastern tributary, There is limited melting in this region, so volume loss can occur via basal melt via ocean water or calving. Even in a warm summer there is little visible evidence of surface melting in 2015. The widespread loss of mass from ice shelves in Antarctica is mainly via basal melting (Paolo et al, 2015). An examination of the coast in the region illustrates numerous other examples where glacier retreat has led to separation of islands, such as with the loss of the Jones Ice Shelf.

1990 Landsat image

1991 Landsat image

2001 Landsat image

January 2015 Landsat image

Feb. 2015 Landsat image

North Leones Glacier Retreat and new Landslide, Patagonia, Chile

On March 26, 2015May 3, 2024 By mspeltoIn chile glacier melt, chile glacier retreat, glacier climate change, Glacier Observations

Jill Pelto, my daughter returning from fieldwork with UMaine in the Falkland Island took a picture last week out the plane window of Leones Glacier of the northern Patagonia Icefield. The picture illustrated two changes worth further examination, and the fact that if you have a glacier picture that you would like more information on let me know. The picture indicates outlet glaciers of the Northern Patagonia icefield fed by the snowcovered expanse. Also evident is a large landslide that is both fresh and that I knew had not been there before, orange arrow,and it showed a new lake had formed due to retreat of the glacier north of Leones Glacier, red arrow, hereafter designated North Leones Glacier. The landslide extends 2 km across the glacier and is 3 km from the terminus. Here we use 1985 to 2014 Landsat imagery to identify changes in North Leones Glacier and the landslide appearance.

npi tri glacier — Jill Pelto took this picture on March 13th, 2015

In 1985 there are medial moraines on the glacier surface, but no large landslide deposit. The Northern Leones Glacier terminates on land, red arrow. A distributary terminus almost connects with another glacier to the north at the yellow arrow. In 1987 there is little evident change from 1985. By 2002 a small lake is beginning to form at the terminus of Northern Leones Glacier. By Feb. 2014 a substantial lake has formed at the end of the North Leones Glacier. There is considerable separation between the distributary terminus at the yellow arrow and the next glacier. There is no landslide deposit either. Google Earth imagery indicates the lack of a landslide deposit as well. A closeup of the terminus of North Leones Glacier in 2013, with Google Earth imagery, indicates ogives (blue arrows), which are annually formed due to seasonal velocity changes through an icefall. In January 2015 the landslide deposit is evident, extending about 2 km across Leones Glacier and 3 km from the terminus. The North Leones Glacier has retreated 700 meters from 1985-2015. The retreat of the distributary terminus indicates thinning upglacier of the icefall on North Leones Glacier. The landslide adds mass to Leones Glacier, which will lead to a velocity increase. The debris is thick enough to reduce melting in this portion of the ablation zone. The velocity of this glacier is indicated by (Mouginot and Rignot, 2015) as 200-400 meters per year, indicating that for the next decade at least this landslide will impact the lower Leones Glacier. (Willis et al, 2012) identify thinning of the Leones Glacier area around 1 m per year, which will be reduced on the landslide arm of the glacier.
(Davies and Glasser, 2012), indicate that this region experienced increased area loss from 1986-2011. Lago Leones feeds the Leones River which is also fed by the retreating General Lago Carerra Glacier.

Landsat image 1985

Landsat image 1987

Landsat image 2002

Landsat image 2014

Google Earth Image 2010

Google Earth image 2013

Landsat image 2015

Widespread Retreat Gilkey Glacier System, Alaska

On March 23, 2015May 3, 2024 By mspeltoIn alaska glacier retreat, climate change glacier retreat, glacier climate change, Glacier Observations

Gilkey Glacier drains the west side of the Juneau Icefield and has experienced widespread significant changes since I first worked on the glacier in 1981. Here we examine the changes from the August 17, 1984 Landsat 5 image to the August 21, 2014 image from newly launched Landsat 8. Landsat 5 was launched in 1984, Landsat 8 launched in 2013. The Landsat images have become a key resource in the examination of the mass balance of these glaciers (Pelto, 2011). The August 17th 1984 image is the oldest Landsat image that I consider of top quality. I was on the Llewellyn Glacier with the Juneau Icefield Research Program (JIRP) on the east side of the icefield the day this image was taken. JIRP was directed by Maynard Miller at that time and by Jeff Kavanauagh now. The Gilkey Glacier is fed by the famous Vaughan Lewis Icefall at the top of which JIRP has its Camp 18 and has monitored this area for 60 years. Here I examine changes both in images and text below. The same analysis in a more depth is contained in the screen capture video of the same images. Choose the format you prefer and let me know which works for you.

There are seven locations noted in the 1984 and 2014 image that are the focus of more discussion in a set of three more focused images

1984 Landsat Image

2014 Landsat image

Arrow #1 indicates the Gilkey Glacier terminus area. Gilkey Glacier had begun to retreat into a proglacial lake by 1984, the lake was still just 1 km long. A short distance above the terminus the Gilkey was joined by the sizable tributaries of the Thiel and Battle Glacier. By 2014 the main glacier terminus has retreated 3200 m, the lake is now 4 km long. A lake that did not exist in USGS maps from 1948. Thiel and Battle Glacier have separated from the Gilkey Glacier and from each other. Thiel Glacier retreated 2600 m from its junction with Gilkey Glacier from 1984-2014 and Battle Glacier 1400 m from its junction with Thiel Glacier and 3500 m from the Gilkey Glacier. Melkonian et al (2013) note the fastest thinning in the Gilkey Glacier system from to is near the terminus and in the lower several kilometers of Thiel Glacier.

Above: 1984-2014 Comparison of Gilkey Glacier terminus area with Landsat imagery

Arrow #3 and #4 indicates valleys which tongues of the Gilkey Glacier flow into. In 1984 at #3 the glacier extended 1.6 km upvalley ending where the valley split. The portion of the Gilkey flowing into the valley had a medial moraine in its center. At arrow #4 the glacier extended 1.5 km up Avalanche Canyon. In 2014 at #3 the glacier tongue ends 1.2 km from the valley split, and the medial moraine does not enter the valley. At #4 the glacier has retreated 1.3 km, leaving this valley nearly devoid of a glacier.

Above: Comparison of the Avalanche Canyon area 1984-2014.

Further upglacier arrow #5 indicates a side glacier that in 1984 featured an unending system of glacier flowing down the steep mountain sides into the valley bottom. By 2014 two rock ribs extend along most of the east and west valley walls separating the glaciers on mountain side from the main valley glacier, which has as a result been reduced in width and velocity. At arrow #6 a tributary glacier is seen merging with Gilkey Glacier in 1984. By 2014 this tributary no longer reaches the Gilkey Glacier, ending 300 m up the valley wall. At arrow #7 the Little Vaughan Lewis Icefall in 1984 is seen merging with the Gilkey Glacier across a 300 m wide front. This I can attest from seeing the glacier that summer to be an accurate observation. By 2014 at arrow #7 the Little Vaughan Lewis Icefall no longer feeds ice directly to the Gilkey Glacier. There is still avalanching but not a direct flow connection. JIRP has Camp 19 in this area, a spectacular area of ongoing research by JIRP. The main Vaughan Glacier Icefall is still impressive, just south of the rib beyond arrow #7. Measurements of snowpack are made annually by JIRP above the icefall, and indicate a mean snow depth exceeding 3 m in early August, note image below of measuring annual snow layers in a crevasse at head of the icefall. Pelto et al (2013) summarize the results of this ongoing research that Chris McNeil (USGS) is working to enhance with newer technology. The terminus change of all Juneau Icefield glaciers from 1984-2013 has been summarized in a previous post. The 2015 season will be of interest, since the area had a remarkably warm yet wet winter. This will lead to high ablation at lower elevations, likely a higher snowline than usual, but above the Vaughan Lewis Icefall will those warm wet events dumped snow? The 2014 winters season was warm and the snowline seen in the 2014 satellite imagery was at 1500 m, yet snowpack at 1760 m on the Vaughan Lewis Glacier was 3.3 m deep in late July. This has been the case in the past with warm wet winters featuring heavy snow above 1600 meters on the icefield. JIRP will be in the field answering this question in 2015.

Above: Comparison 1984-2014 of the Vaughan Lewis Glacier area

Crevasse stratigraphy Vaughan Lewis Glacier.

Downwasting Tributary-Glacier Dammed Lake Formation at HPN4 Glacier, Patagonia, Chile

On March 19, 2015May 3, 2024 By mspeltoIn chile glacier melt, chile glacier retreat, glacier climate change, Glacier Observations

We often are more concerned with what is happening at the terminus of a glacier; however, often key changes are happening up glacier some distance. This is the case with the following example. The Northern Patagonia Icefield (Hielo Patagónico Norte, HPN) is one of the two main icefields in Patagonia. The remoteness of the region is evidenced by the number of significant lakes and glaciers that remain unnamed. This remoteness has led to several valuable detailed recent studies utilizing satellite imagery on glacier extent (Davies and Glasser, 2012), glacier thickness change (Willis et al, 2012) and glacier velocity (Mouginot and Rignot, 2015) Here we focus on a downwasting tributary to an unnamed glacier listed as HPN4 Glacier in the aforementioned studies. Davies and Glasser, (2012) identify this region of the icefield as retreating faster from 2001-2011 than during any measured period since 1870. Willis et al, (2012) in their Figure 2, seen below, identify this an area of pronounced thinning, approximately 5 m/year from 2000 to 2011. Why such rapid thinning in an area without calving? Mouginot and Rignot, (2015) indicate that this area is not an area of rapid flow, and given the thinning it should be an area of diminishing flow. Here we examine changes from 1987 to 2014 using Landsat imagery.

Digital Globe image of southern section of Northern Patagonia Icefield, with black arrow indicating downwasting tributary from the east flowing into HPN4 Glacier.

Figure 2 from Willis et al (2012) indicating thinning of NPI glaciers from 2000-2011, the blue arrow indicates the downwasting tributary of interest flowing into HPN4 Glacier from the east.

Ice Flow direction for HPN4 Glacier and the downwasting tributary (DT). The flow diagram above indicates the converging flow of the downwasting tributary and HPN4, that meet at the medial moraine.

In 1987 there are five contributing glacier tongues to the downwasting tributary, each indicated with a red arrow. It is like a bathtub being filled with five taps at once. The yellow arrow indicates a medial moraine at the mouth of the valley, signalling the lack of current contribution of the downwasting tributary to HPN4 Glacier. By 2004 only three of the contributing glacier tongues still merged with the downwasting tributary, and two of these are much more tentative. The medial moraine has shifted east indicating that the main HPN4 Glacier is now flowing into the valley instead of the downwasting tributary being a contributing tributary to HPN4. By 2014 there is only one contributing glacier tongue to the downwasting tributary, only one tap for this draining bathtub, the other four contributing tongues have retreated from contact with the downwasting tributary. The medial moraine has spread eastward and some fringing proglacial/subglacial lakes are evident. In 2015 the only change is that the rifting near the medial moraine is more pronounced. A closeup 2013 Digital Globe image indicates both fringing ponds-blue arrows, rifts caused by varying flotation-green arrows and expanding supraglacial ponds, red arrows. The rifts are a sign of instability and typically lead to break up of this portion of the terminus. The downwasting tributary continues to demise faster than HPN4 Glacier, which crosses the valley mouth, hence it is likely that a glacier dammed lake will form and that HPN4 Glacier will continue to flow further east up this valley, which could offset some of the downwasting and lake development. In either case this redirected flow of HPN4 into a high ablation valley, will help encourage a faster retreat of the main terminus. How large the lakes gets and how much of the time it is filled are difficult to speculate upon. Analogs for this type of lake are seen at. Allemania Glacier (Lago Martinic) and Baird Glacier (Witches Cauldron) . Schaefer et al (2013) discuss the HPN4 Glacier because the main terminus has changed little given its modelled mass balance, and the modelled mass balance to the east appears too negative, which they suggest indicates wind redistribution from the HPN4 to the Pared Sud Glacier just east. That is a challenge to sort out without some ground truth.

1987 Landsat image

2004 Landsat image

2014 Landsat image-not the fringing blue indicating trapped sub-glacial/proglacial lake.

2015 Landsat image

Google Earth image 2013

Conway Glacier Separation and Retreat, Alberta

On March 16, 2015May 3, 2024 By mspeltoIn alberta glacier retreat, Canada glacier retreat, climate change glacier retreat, Glacier Observations

Conway Glacier drains east from the border with British Columbia into the Howse River. The Howse River joins the Saskatchewan River upstream of the Bighorn Hydropower project, which impounds Lake Abraham and produces 120 MW of power. The map of this area was updated based on 1990 images which indicate Conway Glacier is comprised of two lobes that join near the terminus. An inventory of glaciers in the Canadian Rockies indicate area loss of 15% from 1985 to 2005 (Bolch et al, 2010). The more famous Columbia Icefield, 50 km north, has lost 23 % of its area from 1919-2009 with ice loss at a minimum during the 1970′s (Tennant and Menounos, 2013). Here we examine Landsat imagery from 1986 to 2014 to see the impact of recent climate change.

Map of Conway Glacier area from 1990 image.

In 1986 the two glaciers are still joined, with a surface lateral moraine at their junction, orange dots indicate this narrow surface rock band eroded from the ridge between the two lobes. The yellow arrow in each image indicates the 1986 terminus location of the northern lobe, the red arrow indicates a bedrock step near the southern lobe terminus, green arrow indicates an ice filled basin, and the purple arrow a small tributary joining the main glacier. In 1986 the southern lobe extends 300 meters beyond the bedrock step. By 1994 a small lake is developing at the basin indicated by the green arrow and the northern lobe is reduced in width. Overall less than 40% of the glacier is snowcovered. By 1998 the southern lobe has retreated to the bedrock step and the northern lobe has retreated from the end of the lateral moraine. The glacier again is less than 40% snowcovered. The 2013 image has better resolution thanks to the better Landsat 8 imagery, and has been sharpened using a higher resolution panchromatic image layer by Ben Pelto (Technique will be explained in a future post). The glaciers are no longer joined. The northern lobe has retreated 500-550 m since 1986 and a small lake has formed at the 1986 terminus location, another yellow arrow indicates 2013 terminus. The northern lobe has retreated above the bedrock step, a total retreat of 500-600 m since 1986. Two additional red arrows have been added to indicate 1986 and 2013 terminus location. The small lake at the green arrow has expanded. The tributary connection at the purple arrow is nearly severed. Retained snowpack on the glacier is also limited in area with most of the glacier in 2013 being bare glacier ice. This indicates that snow was not retained in recent previous years either. For a glacier to be in equilibrium it needs more than 50% of its area to be covered by snow at the end of the melt season, not 35% with a few weeks left in the melt season. as in 2013. This glaciers retreat and volume loss mirrors that of the region including Saskatchewan Glacier and Fraser Glacier. Peyto Glacier is the nearest glacier, just 20 km southeast, with a long term mass balance record, which indicates a cumulative loss or over 28 m w.e or 30 m of glacier thickness.

1986 Landsat image

1994 Landsat image

1998 Landsat Image

2013 Landsat image-Pan sharpened by Ben Pelto (Univ. Northern British Columbia)

Demise of Antler Glacier, Juneau Icefield, Alaska

On March 12, 2015May 3, 2024 By mspeltoIn glacier climate change, Glacier Observations

“What is wrong with this map?” . Was my first comment about the Antler Glacier in 1981, while surveying the geology in the region with the Juneau Icefield Research Program, during light snow flurries in August. The map I had was the most up to date USGS topographic map based on 1948 images, indicating Antler Glacier terminating in a small lake. By 1981 the lake was quite long and the glacier no longer reached it, though this was not perfectly evident through the snow flurries. If I returned to the same location today, looking at the updated USGS topographic map from 1979 my comment would be the same. Climate is changing our glaciers and our maps of these regions. The Antler Glacier is an outlet glacier of the Juneau Icefield. It is actually a distributary glacier of the Bucher Glacier. It splits from the Bucher Glacier 8.5 km above where the Bucher Glacier joins the Gilkey Glacier as a tributary. In 1948 it spilled over the lip of the Antler River valley from the Bucher Glacier and flowed 6 kilometers downvalley to end in a proglacial lake. The glacier was 6200 m long in 1948, red arrow is 1984 terminus, yellow arrow indicates 2014 terminus. Here we examine satellite imagery from 1984 to 2014 to identify changes in the Antler and other small glaciers in the area.

USGS map showing 1948 position of Antler Glacier.

Antler Glacier in 1979

In each Landsat image the arrows indicate the same location, red arrow 1984 Antler Glacier terminus location, yellow arrow 2014 terminus of Antler Glacier, green arrow small glacier adjacent to Antler Glacier and purple arrow tributary glacier to Antler glacier. In 1984 Antler Glacier no longer reached Antler Lake which had expanded from a length of 1.6 km in 1948 to 4.2 km. The glacier was still 2.7 km long. Though I was in the area in 1984 I did not see Antler Glacier. The small glacier at the green arrow terminated at the edge of a small lake. The tributary at the purple arrow joined the Bucher Glacier. By 1997 the lower 2 km of the Antler Glacier were gone and the glacier ended near the base of the steep eastern entrance to the valley. The glacier at the green arrow no longer reached the lake and at the purple arrow the tributary has separated from Bucher Glacier. By 2013 Antler Glacier extended only 400-500 m over the lip of the valley entrance from Bucher Glacier. The glacier at the purple arrow was separated by more than a kilometer from the Bucher Glacier. There is little change of course from 2013 to 2014, Antler Glacier has retreated 2.2 km since 1984 and 5.8 km since 1948. The small glacier at the green arrow has receded 300 m from the lake shore. The former Bucher tributary at the purple arrow now terminates 1.4 km from Bucher Glacier.

The lake is gorgeous, and the valley once filled by the glacier is now nearly devoid of glacier input. The retreat is largely a result of reduced flow from the thinning Bucher Glacier which no longer spills over the valley lip significantly. As the Bucher Glacier continues to thin, the Antler Glacier will cease to exist. This thinning is due to increased ablation of the glacier. The mass balance loss at nearby Lemon Creek Glacier from 1953-2011 was -26.6 m Pelto et al (2013), this equals a thinning of at least 29 m. Gilkey Glacier which is fed by Bucher Glacier has retreated 3.2 km from 1984-2013 and 4 km from 1948-2013 (Pelto, 2013). Continued losses and separation of tributaries from the Bucher Glacier could lead to formation of glacier dammed lakes such as on Tulsequah Glacier. The Juneau Icefield Research Program directed by Jeff Kavanaugh will again be in the field in 2015., I will be interested to see their observations after the exceptionally warm but wet winter in the regione

1984 Landsat image

1997Landsat image

2013 Landsat image

2014 Landsat image

Cordillera Lago General Carrera Glacier Retreat, Chile

On March 10, 2015May 3, 2024 By mspeltoIn chile glacier melt, chile glacier retreat, Chile glaciers and hydropower, glacier climate change, Glacier Observations

You know southern Chile has lots of glaciers when an icefield with an area of 132 square kilometers has no named glaciers. Davies and Glasser (2012) referred to this icefield as Cordillera Lago General Carrera, since it drains into that lake, the icefield is just east of the Northern Patagonia Icefield. Davies and Glasser (2012) noted that the icefield has a mean elevation of 1670 m and has declined from an area of 190 square kilometers in 1870, to 139 square kilometers in 1986, and 132 square kilometers in 2011. They further noted that the area loss of Patagonia glaciers has been most rapid from 2001 to 2011. Paul and Molg (2014) observed a more rapid retreat of 25% total area lost from glaciers in northern Patagonia from 1985-2011, the study area was north of the Northern Patagonia Icefield. Lago General Carrera drains into the Baker River, which is fed by most glaciers on the east side of the Northern Patagonia Icefield. This river had a series of proposed hydropower projects that have now been cancelled by the Chilean government.

Here we examine Landsat imagery from 1987 to 2014 to identify the changes in a pair of outlet glaciers that drain the eastern side of the icefield, images below. In 1987 both outlet glaciers terminated in an unnamed lake that drains into the Leones River. The southern glacier is 5.5 km long beginning at 2400 m and terminates at the yellow arrow, with the snowline marked by purple dots, in the images below. The northern glacier is 5.0 km long beginning at 2200 m with the terminus at the red arrow. In 1987 the glaciers were in shallow enough water that calving was limited and no icebergs are evident. By 2001 both glaciers are no longer terminating in the lake. The retreat can no longer be enhanced by calving into the lake. By 2014 both glaciers have retreated several hundred meters from the lake. It is easier to measure the retreat in the 2013 Google Earth image. The retreat from the 1987 to 2013 position are indicated by the pair of arrows. The northern glacier has retreated 400 m and the southern glacier 600 m from 1987 to 2013. In both cases this is approximately 10% of the glacier length. The beautiful green color of the lake is indicative of the contribution of glacier flour from actively moving and eroding glaciers. This glaciers retreat is similar to that of the nearby Nef Glacier and Verde Glacier.

1987 Landsat image

2001 Landsat image

2014 Landsat image

2013 Google Earth image. With arrows indicating terminus change from 1987 to 2013.

Moving to AGU Blogosphere

On March 9, 2015 By mspeltoIn Glacier Observations1 Comment

As of today this blog is shifting to the AGU Blogosphere. The blog has the same name and will have the same approach with two blogs a week on a the response of glaciers to climate change, one glacier at a time. If you have been a follower of this blog, please follow there. Note all the posts have been migrated there too.

Thanks for the continued support and interest.

http://blogs.agu.org/fromaglaciersperspective/

Mauri Pelto

Field Observations on Lower Curtis Glacier

On March 6, 2015March 6, 2015 By mspeltoIn Glacier Observations

This is a visual introduction to our 31 years of work on Lower Curtis Glacier complimented with Google Earth imagery to illustrate the changes. Each year since 1984 this glacier has received an annual checkup from us, North Cascade Glacier Climate Project. The mass balance and retreat of this glacier is reported to the World Glacier Monitoring Service. Many nights have been spent camped below this glacier. Unfortunately in the last seven years we have had mostly wet weather at this site, that hopefully will not be repeated this coming summer.

Zongo Glacier Retreat, Bolivia 1994-2014.

On March 1, 2015March 1, 2015 By mspeltoIn bolivia glacier retreat, Glacier Observations4 Comments

Zongo Glacier, Bolivia extends 2.9 km down the south side of Huayna Potosi from 6000 m to 4900 m. Zongo Glacier is a small valley glacier located 30 km north-east of La Paz, and its runoff is directed to an important hydraulic power station which supplies La Paz. Note Laguna Milluni in foreground of the first image. The dam is visible as is the power station to the right and below the lake. The glacier has considerable snowcover on its upper section and crevassing. This indicates a persistent accumulation zone. In 1991 a glaciological research program was established on Zongo Glacier to monitor mass balance, understand its hydrology and energy balance. The long term director of this research Bernard Francou has been called the glacier guardian. The cumlative mass balance of the glacier from 1991-2013 has been -6.5 m water equivalent. The typical Alpine glaciers undergoes a long accumulation period in winter and a short ablation season in summer. The glaciers of the tropical Andes experience snow accumulation during the wet season, austral summer on their upper regions and maximum ablation during the same season low on the glacier. In the dry season winter there is a period of low ablation over the whole glacier. Mean annual air temperature at the long term snowline at 5250 m is -1.5 °C. Mean precipitation is about 0.9 m/year.
Google Earth image-Huayna Potosi and Zongo Glacier

Since 1991 the glacier has lost more than 7 m of thickness and has retreated significantly. The mass balance loss has been most pronounced during El Nino periods. La Nina’s are associated with positive or only slightly negative mass balance. Here we examine Landsat imagery and Google Earth imagery form 1994 to 2014.

In 1994 there is no lake at the terminus of the glacier, red arrow. By 2004 the Google Earth image indicates the glacier terminating along the northeast shore of the lake, a 90 m retreat in a decade. By 2008 the glacier no longer reaches the edge of the lake, but the front is still crevassed. In 2014 the glacier terminates 100 meters from the lake. Total retreat during the 20 year period is 220 m. The current terminus in 2014 is dirtier and less crevassed than in 2004, and less crevassed than in 2008. The lower 200 m of the glacier is thin, narrow and lacks active crevassing. This relatively stagnant area will melt away in the next decade.

Zongo Glacier continues to have an accumulation zone, a necessary essential for glacier survival, and unlike the nearby Chacaltaya Glacier which disappeared in 2009, it will exist for sometime. The Chacaltaya Glacier is a small glacier, like 80% of the glaciers in this region of the Cordillera Real, and its disappearance puts more pressure on the water resources provided by the larger remaining glaciers such as Zongo Glacier. Rabatel et al (2013) note the striking rise in the freezing levels in the region due both to higher temperatures and more convective activity that is a particular threat to glacier survival.

1994 Landsat image

2004 Google Earth image

2008 Google earth image

2014 Google Earth image

2014 Landsat image

Mahsa Icefield Retreat and Separation, Baranof Island, Alaska

On February 26, 2015 By mspeltoIn alaska glacier retreat, Glacier Observations2 Comments

The Mahsa Icefield is at the headwaters of Takatz Creek. This is a small glacier, not an actual icefield. Five kilometers to the west is another small unnamed glacier at the headwaters of Sawmill Creek. Here we focus on changes in the two glacier using Landsat images from 1986 to 2014.

Google Earth image

In 1986 the Mahsa Icefield is a contiguous glacier that extended 5 km from east to west, red arrow indicates the mid-section of the icefield. A separate glacier in Sawmill Creek, yellow arrows, was 2.1 km long and has no lake at its terminus. In 1997 the Mahsa Icefield has separated into an east and west half, at the red arrow, and has lost all of its snowcover. The glacier in Sawmill Creek is still a single ice mass, but has lost all of its snowcover, which happened in 1998, 2003 and 2004. In 2014 the Mahsa Icefield’s east and west half are separated by 300 m, red arrow. There is very little snowcover remaining despite there is a month left in the melt season. At the headwaters of Sawmill Creek a lake has formed as the glacier has retreated, the lake is 600 m long in 2014. The glacier has also separated into a small upper and lower section. This glacier has lost half of its area since 1986. The retreat of these glaciers on Baranof Island is similar to the retreat of nearby Carbon Lake Glacier,Lemon Creek Glacier, and Sinclair Glacier. Lemon Creek Glacier has lost more than 25 m of glacier thickness during the 1953-2014 period when its mass balance has been observed by the Juneau Icefield Research Program, and has retreated more than 1 km (Pelto et al, 2014).